1. Field of the Invention
The invention relates to compacting machines and, more particularly, relates to improvements in a vibratory plate machine of the type used to smooth and/or compact sand, gravel, crushed aggregate, and hot and cold asphalt.
2. Discussion of the Related Art
Vibratory plate machines, usually known simply as "vibratory plates" are widely used in the construction and landscaping industries for the compaction of granular materials. Applications include the compaction of sand, gravel, or crushed aggregate for foundations, footings, or driveways; base preparation for concrete slabs, asphalt parking lots, etc.; and the compaction of either hot or cold mix asphalt during patch or repair of streets, highways, sidewalks, parking lots, etc. The typical vibratory plate machine includes a baseplate that performs the actual compacting operation and a console that is mounted on the baseplate so as to support an engine and its associated equipment. An eccentric shaft device, commonly known as an exciter, is located on the baseplate in an underlying relationship to the console and is driven by the engine to impart vibrations to the baseplate, thereby compacting materials on which the machine rests. Movement of the machine is controlled by a handle assembly extending upwardly and rearwardly from the console. In hot mix asphalt compaction applications, the machine is additionally provided with a water tank and associated equipment for spraying water on the surface immediately in front of the machine to prevent the asphalt from congealing on the baseplate.
The typical vibratory plate machine on the market today exhibits several drawbacks and disadvantages.
First, the typical vibratory plate machine is somewhat difficult to control and maneuver due in part to the profile of its bottom or compaction surface. The "profile" drawback resides in the fact that the baseplates of most traditional vibratory plate machines have a flat or planar bottom surface so that the entire bottom surface of the baseplate rests upon the surface being compacted with equal force. The resulting uniform distribution of friction significantly hinders maneuverability both fore and aft and side to side. Moreover, any rocking motion of the machine tends to ridge or otherwise mar the surface being compacted. Ridging or marring is particularly undesirable in asphalt compaction operations because, once the asphalt hardens, the paved surface is permanently marred.
At least one company attempted to alleviate these problems by imparting a slight angle or V-shape to the bottom surface of the baseplate. The vertex of the V is centered on the baseplate and runs longitudinally along the entire length of the baseplate. This design, which was developed by the assignee of this application, proved only partially effective in solving either the maneuverability problem or the ridging problem.
Maneuverability of the typical baseplate is also hindered by the general shape of it. Specifically, when viewed in bottom plan, the typical baseplate is perfectly rectangular. Some more sophisticated baseplates curl upwardly at their front and rear ends, but they still have a constant width. Accordingly, they are difficult to maneuver around corners and other obstructions.
Another problem associated with typical baseplates results from the configuration of the reinforcing ribs. Reinforcing ribs are sometimes provided on the upper surface of the baseplate to increase strength and durability. However, these ribs were heretofore configured without giving consideration to debris removal. Debris tends to fall onto the baseplate from adjoining sections of the surface during the compaction operation and to accumulate as the compaction operation continues. Reinforcement ribs and other structures on traditional baseplates tend to trap this debris on top of the baseplate, adding to the machine's weight, endangering contamination of otherwise-clean surfaces when the machine is tilted on its side or otherwise moved during operations following the compaction operation, and hindering cleaning of the machine.
Second, the console of the traditional vibratory plate machines also exhibits several disadvantages because it is formed from weldments. For instance, it is labor intensive to assemble. Many different component plates (typically 25 or more) must be machined and welded together to form the console. Moreover, the relatively heavy welded steel console undesirably increases the overall weight of the machine, thereby decreasing stability and maneuverability. The welded connections between the vertical edge plates of the console and the main horizontal plate also prevent connection of shockmounts to the extreme corner portions of the console. Elastomeric shockmounts are used to mount the console on the baseplate to reduce the imposition of vibrations on the console from the baseplate. Stability and vibration reduction measures are most effective when imposed at the extreme corners of the machine. (This principle is illustrated by recent "cab-forward" trends in automotive design which seek to improve stability by supporting the automobile chassis as near as possible to its extreme corners). Hence, by requiring that shockmounts be moved towards the center of the machine, the traditional welded console significantly frustrates attempts to increase stability and reduce vibrations.
Third, most vibratory plate machines exhibit a persistent problem of excessive belt wear because the driven pulley on the exciter and the drive pulley on the clutch are mounted on separate components of the machine (namely, the baseplate and the console, respectively) that can move relative to one another during operation of the machine. This relative movement exerts substantial jerking on the belt, leading to its rapid wear and early failure.
Fourth, most vibratory plate machines incorporate insufficient measures to 1) protect the engine and other sensitive external components in the machine from damage from external shocks and 2) facilitate lifting of the machine for site-to-site transport.
The need has therefore arisen to provide an improved vibratory plate machine lacking some or all the disadvantages described above.